SLI Bandwidth question

Is there any difference in putting..Lets say 2 7950s in a A8N-SLI Which saids it has X8 Speed, And Put 2 7950s in a A8N32-SLI Which said it has X16 Speed. Is there any difference? Will the SLI not work, or will it be significantly slower?

Thats a AM2 board right? =O I'm kind of limited to 939 because i just need to replace my A8N32 but the problem is that i can't find any in American e-tailers =[ But i'm seeing alot of A8N-SLI's so....yeah =D